1. Field of the Invention
Embodiments of the invention are directed to the field of biomedical optics; more particularly to apparatus and methods for examining an excised, radiographically labeled tissue specimen; most particularly to apparatus and methods to aid in the dissection and evaluation of radiographically labeled, excised breast tissue, and other applications.
2. Description of Related Art
Radiological examination such as projection x-ray, computer aided tomography (CAT), magnetic resonance imaging (MRI) or ultrasound can detect tumors inside a patient assuming that the lesion has sufficient contrast. If the tumor needs to be surgically excised, the location of the lesion can be marked using a wire or other structure inserted under radiographic guidance. This is routinely done in breast cancer lumpectomy resection. This wire, often referred to as a guidewire, is either radio-opaque or has contrast under the radiographic imaging technique so it can be seen as it is positioned with respect to the tumor. This guidewire can be subsequently used by the surgeon to direct the excision of the tumor and by the pathologist who inspects the excised specimen to determine if the entire tumor was removed. The ability to locate the end of a radiographically placed marker in an excised specimen is of great interest and has applications in the pathological examination of excised tissue. Knowing the location of the marker or structure within the excised surgical specimen will allow for guided dissection of the specimen such that the region of interest is exposed.
Presently, surgical specimens with embedded guidewires such as excisional breast biopsies are imaged with projection x-ray systems to confirm the presence of the lesion and guidewire, and then examined by a pathologist. The pathologist inspects the specimen by appearance and by feel to determine the likely location of the tumor. After examining the tissue, the pathologist grossly dissects the specimen into slices for additional visual inspection and submission for additional histological processing and microscopic inspection. If the presence and edges of the tumor are not visually or tactilely apparent, the adequacy of surgical excision often cannot be confirmed during the surgery and instead is later determined by viewing the pathology slides prepared from the specimen. Thus it is common for the outcome of the surgery to be unknown for several days.
While initially examining the tissue, care is taken not to over manipulate the specimen during the initial inspection and dissection so that the overall geometry of the tissue is preserved and surgical margins are not disrupted. Many tissues such as breast tissue are quite pliable and, therefore, the post excision x-ray does not provide guidance to the location of the tumor as it is being examined by the pathologist since merely moving the tissue can change its geometry. Additionally, non-palpable tumors, for example breast tumors less than 1 cm, cannot be routinely located by the pathologist examining the tissue. Consequently there is often no means to inform the pathologist of the location of a non-palpable tumor within a surgical excision even if the location of the tumor was marked radiographically prior to excision.
In view of these considerations and the recognized problems associated therewith, the inventors have recognized the value of a solution that provides guidance for the dissection, and assistance in the examination, of the specimen for unusual tissue, cellular, or sub-cellular structures indicating abnormalities such as a tumor or disease state. Advantageous solutions are in the forms of an apparatus (or system) and method to assist the pathologist in locating a radiographically placed marker within an excised specimen in order for the pathologist to orient the specimen, dissect the specimen, and then quickly and reliably check for the presence of a tumor (or other disease state or condition) within the specimen and adjacent to the surgical margins of the specimen so that the surgeon has the information necessary to satisfactorily complete the excision of the tumor or lesion during the initial surgery. Further advantageous aspects of the solutions involve mechanically stabilizing the tissue and the radiographic marker through the use of rapidly polymerizing hydrogels, such that the geometry of the system is stable throughout the handling process; determining the location of the embedded radio-opaque marker through the intact specimen, allowing for guided dissection of the specimen such that the region of interest is exposed; optically segmenting the sliced specimen into its main tissue components, e.g., adipose tissue, fibrous tissue, and epithelial tissue; communication of the segmentation to a display for viewing and assessment; microscopic examination of the surface epithelial content of the specimen and display of the microscopic images for assessment of the cellular and sub-cellular features.